This invention relates to an apparatus for performing recording and/or reproducing of information on a recording medium such as magnetic or magneto optical disc contained in a hard cartridge, which is generally referred to as a disc drive. This invention is particularly usefull when applied to the disc drive used with a disc cartridge containing a magneto optical disc.
A typical type of the conventional disc drive is composed substantially of a base plate on which mechanisms including a pick-up device and a spindle required for the recording/reproducing operation, a sliding plate attached slidably to the base plate and a loading chassis for accommodating a disc cartridge. The loading chassis is moveable in a vertical direction between an operative position wherein it is located near the base plate to be ready for the recording/reproducing operation and a standby position wherein it is retracted from the base plate. The loading chassis ascends along with advancement of the sliding plate in the cartridge ejecting operation and, in turn, descends along with insertion of the disc cartridge into the loading chassis. More particularly, as the sliding plate is advanced against a biasing force of a spring connected thereto, loading chassis which has been standing in the lower operative position is elevated toward the upper standby position due to engagement between guide rollers protruded outwardly from opposite sides of loading chassis and upwardly inclined cam ridges of walls usptanding from opposite sides of sliding plate. There is also provided means for retaining the sliding plate in the fully advanced position which causes the loading chassis to remain standstill in the standby position. Such locked condition of the sliding plate is released when the disc cartridge is inserted to the loading chassis which has been held in the standby position, whereupon the sliding plate is sprung back toward the cartridge unloading direction to thereby descend the loading chassis toward the lower operative position.
The said means for retaining the sliding plate in the advanced position is, for example, disclosed in Japanese Patent Provisional Publication No. 61-292261 wherein the base plate is provided with a latch mechanism adapted to be engaged with a notch formed in the sliding plate. The latch mechanism becomes free from engagement with the notch when the front edge of the disc cartridge push forward a pin of the latch mechanism during advancement of the disc cartridge.
With the above described construction and arrangements of the conventional disc drives, engegement between the guide rollers of the loading chassis and the cam formed integral with the sliding plate will will continue even after the sliding plate has been released from the locked condition to descend the loading chassis to the lower operative position. This means that an external force, which might be applied to the sliding plate by an accidental touch of its leading end which is in the cartridge full-loaded condition protruded to a considerable extent from the front panel of the apparatus would be transmitted to the loading chassis to thereby oscillate the same, resulting in failure of definite positional relationship between the disc and the pick-up mechanism during the recording/reproducing operation. Such transmission of the external force should be avoided especially when a disc drive is used in association with a magneto optical disc cartridge.